Choosing a Safe Mooring Spot for a Small Boat

Start With the Chart, Not the Anchor

Before you think about chain or rope, you need to know what is under the boat and how much water will be there in six hours' time. A small-craft chart shows soundings in metres below chart datum, and the drying heights are the figures worth hunting for with a highlighter. Those underlined numbers are depths above chart datum, so a spot marked 1.4 dries by nearly a metre and a half at low water. Add the predicted height of tide for the nearest standard port and you have a sensible working depth.

Do not rely on one echo sounder reading taken in a swell, and never assume last season's dredged channel is still there. Harbour entrances shift with every winter gale, and a sandbar you crossed comfortably in June may be a metre shallower by October. Look for transits, leading marks and bearings on fixed objects ashore, then write them down. If you cannot identify where the deep water runs, pick another spot.

Shelter Is About Direction, Not Just Walls

A high harbour wall feels reassuring until the wind swings. What matters is fetch — the distance of open water the wind has crossed — and whether you are on a lee shore, with the breeze pushing you towards land rather than away from it. A bay that is perfect in a south-westerly can be a washing machine in a stiff north-easterly, with waves curling round the headland and rebounding off the cliffs.

Think about the forecast for the whole night, not the next hour. If the wind is expected to veer forty degrees, ask yourself where that leaves you. Local effects matter enormously: sea breezes that fill in during the afternoon, gusts funnelling down a valley, and the steep, uncomfortable chop that builds at an entrance when wind runs against tide. The best anchorages work in two or three directions, so you can move a hundred metres and be comfortable again.

Tides Change Everything, Especially Here

British waters have some of the largest tidal ranges in the world. Spring ranges reach twelve metres or more in the Bristol Channel and the Severn approaches, around eight to nine metres at Liverpool, and a more modest three to four metres along much of the south and east coast. That difference decides whether a quiet pool becomes a mudflat, and whether your keel is still floating at breakfast.

Learn the rule of twelfths: in a six-hour rise, roughly one twelfth of the range comes in the first hour, two in the second, three in the third and fourth, two in the fifth and one in the sixth. It is a handy mental check when the tide table seems to be telling you something unlikely.

Also find out what the seabed is made of. Soft mud holds well and dries kindly; hard sand and shingle can look perfect and offer almost nothing. Near harbour walls, scour can leave a channel deeper than the chart suggests, so watch where local boats lie and ask about it.

Ask Before You Swing: Local Rules and Courtesy

Harbours are working places, not free car parks. In most UK harbour towns you need the harbourmaster's permission before anchoring, and there are byelaws covering everything from speed limits to where you may leave a dinghy. Visitor moorings and pontoons usually carry a charge, and paying it is both a courtesy and a form of insurance: you are expected, visible, and someone will keep half an eye on you.

• Keep clear of fairways, ferry routes, racing marks and mooring trots.
• Never anchor over a submarine cable, a pipeline, or inside a marked conservation area where anchoring is restricted.
• Listen on the radio before you transmit, and use the harbour's working channel once you know it.
• Introduce yourself at the harbour office or boatyard. The person with the driest oilskins usually knows where the holding is best.

Ground Tackle That Earns Its Keep

Match your anchor to the seabed and the size of boat, then give it a chance. As a rough guide, lay out four to seven times the depth in chain, more in strong winds or if you are using rope, and let the boat settle astern under gentle power to prove the anchor has bitten. A short burst of reverse tells you far more than a hopeful stare over the bow.

Carry a second anchor with its own warp or chain, a length of spare line, a sharp knife within reach and a buoyed tripping line if you are anchoring where the hook may snag. Set an anchor alarm on your plotter or phone, but back it up with transits or bearings taken to two fixed points ashore. Electronics fail quietly; your own eyes do not.

Always Have Somewhere Else to Go

The single most useful thing you can carry is a plan. Before you drop the hook, identify a second anchorage within easy reach, ideally one that works in the wind you are expecting and the one after it. Note the entrance, the depth at low water, and whether you can get in after dark. Keep enough fuel, warm clothing and food aboard that a change of plan is an inconvenience rather than an emergency.

Check the inshore waters forecast and the shipping forecast regularly, and take the evening update seriously. If the wind is rising, the holding is doubtful, or the harbour is busy, move while there is still light and still time. A well-chosen mooring is one you can leave comfortably at any hour — and a good sailor is never embarrassed to say that the quiet, sheltered spot down the coast looks rather better after all.